Are there higher potential dividends if I transfer my 401k to a Roth IRA?

If you keep the same investments, then the dividends and earnings should be the same. Think of 401k and Roth IRA as the "baskets" that hold your investments (stocks, bonds, mutual funds, etc.) Switching the investments from one basket to another doesn't change the earnings from these investments.
Switching to an IRA, however, may give you access to more investment options. So by picking better investment options, you can increase your earnings.
Another difference is that a Roth IRA gives you tax-free earnings, that means any earnings from your investment will not be taxed. But you will pay taxes upfront. Whereas with a 401k, you don't pay tax now, but when you withdraw from the 401k, there will be taxes on both the contributed amount and the earnings. Read more about Roth IRA here. 

A conversion to a Roth IRA may or may not make sense for you depending upon a variety of factors, including your current and projected tax bracket, and your other assets.  You should consult a financial adviser for a more detailed analysis of your particular situation.